In this case all we're doing is changing what our second voice is going to be. We start off with a Dm7/11, so we've got an F as our second voice. In the previous few examples, we had D as our second voice. We're always going to have the C to B move because the guide tones, which are the thirds and the sevenths that reside on the third and fourth strings. You're going to see this approach throughout a lot of these ii - V moves.